(1) Field of the Invention
The field of the present invention pertains to a controlled transfer biological collection device using a dry solid storage and transfer medium and a method for the collection of biological material of interest (genetic or proteinaceous material) in a form suitable for storage and/or subsequent analysis. Specifically, the present invention provides for a sampling device that controls the transfer of the biological sample to the storage medium by holding the storage medium and a moveable sample collection member having an analyte collection surface. The invention further provides for a method not only for storing a biological analyte on this collection device but also for analyzing the stored biological analyte using methods that are suited for automated analyzing systems.
(2) Description of the Related Art, Including Information Disclosed Under 37 CFR 1.97 & 1.98
The collection of biological samples (such as blood) and extracting DNA for genetic analysis from the sample has been widely used by the forensics and medical community for identification purposes, for paternity testing, for genetic diagnostic testing in new born screening programs, for genetic typing for predisposition to disease and for genetic characterization for drug susceptibility. However, due to the invasive nature of blood collection, alternative non-invasive methods are coming into favor. Current methods involve scraping cellular mucosa from inside the oral cavity using any of a number of different devices such as cytobrushes, cotton or Dacron swabs, mouthwash swish and rinse methods, foam tipped swabs, and supported cellulosic filter paper collection techniques (known as the Bode method). These methods require time-consuming, labor intensive extraction methods.
The introduction of treated storage matrices into the forensics community has significantly streamlined the collection and extraction of DNA from a variety of samples. The use of FTA® brand treated matrices (from Whatman, Inc. of Florham Park, N.J. USA) with non-invasive buccal cell collection techniques presents a new set of problems. With the use of conventional buccal swabs, one can fail to transfer buccal cells to the treated matrix in a consistent and reproducible manner. If the swab used to collect the sample is separate and distinct from the treated matrix receiving the sample, then forensic traceability issues arise, particularly if the two become separated later in the chain of custody of forensic evidence.
Examples of treated matrices for biological sample collection or storage and associated collection devices can be found in the following US patents: U.S. Pat. No. 6,627,226, U.S. Pat. No. 6,447,804, U.S. Pat. No. 6,294,203, U.S. Pat. No. 6,168,922, U.S. Pat. No. 5,976,572, U.S. Pat. No. 5,972,386, U.S. Pat. No. 5,939,259, and U.S. Pat. No. 5,756,126. Basically, these patents use two different methodologies for stabilizing biological samples.
The first stabilizing method uses a combination of an absorbent material as a storage medium that does not bind to nucleic acids and a chaotropic salt impregnated about the storage medium. (For the purposes of the cited prior art and the present invention, “chaotropic salts” include any substance capable of altering the secondary, tertiary, or quaternary structure of biomolecules in aqueous solution, but leaves the primary structure intact.) Preferably, a chaotropic salt is said to inactivate any nucleic acid amplification inhibitors present in the biological source, by precipitation, by inducing the inhibitor to irreversibly bind to the matrix, or by causing substantially irreversible denaturation of the inhibitor. Suitable chaotropic salts include guanidinium salts such as guanidine isothiocyanate, guanidine thiocyanate, guanidine hydrochloride, sodium iodide, sodium perchlorate, potassium iodide, sodium isothiocyanate, urea, or combinations thereof.
The second stabilizing method also uses a dry solid storage medium but a different adsorbed or absorbed stabilizer. Here, the protectant composition comprises a protein denaturing agent (such as an anionic detergent) and a free radical trap (such as a weak base, and a chelating agent, and optionally, uric acid or a urate salt).